It is often desirable to control the speed at which air can flow through a passage as associated with a pneumatic system, such as by controlling the speed at which exhaust air can escape through a passage. One common utilization of this principle is in association with a double-acting air cylinder for controlling the escape of exhaust air from one or both sides of the cylinder so as to control the piston movement in one or both directions. At the present time, this controlled escape of exhaust air is accomplished by conventional flow-control devices which are installed directly within the air line between the cylinder and the main control valve. Such a conventional flow control device typically employs a one-way ball check valve and an adjustable throttle valve connected in parallel therewith, whereby the device normally allows full flow in one direction, and controlled flow in the other. Such device, however, is expensive and complex, is generally more difficult to install and adjust, and results in the overall system being more complex and less flexible.
In other circumstances, control over the flow of exhaust gas may also be accomplished at the main flow valve, either by an exhaust control(s) built into the valve or by a separate control located between the valve and subplate or manifold. It has generally been preferred to provide a separate control, which control may be installed between the main valve and the subplate or manifold on which the main valve is typically mounted. Such a control, which is generally cheaper than the conventional device as described aforesaid, has conventionally been built utilizing a conventional adjustable needle screw as a throttling member. This type throttling member normally requires that the flow passage undergo a change of direction since the adjustable needle valve can be made to perform a proper and sensitive throttling action only when it is positioned in close proximity to a valve seat, which seat can be properly provided only at a right-angle junction associated with the flow passage. However, in many situations, particularly when mounting a throttle or exhaust speed control valve between a main valve and a manifold or subplate, it is not practical to change the flow direction within a device possessing the necessary simplicity and compactness, and hence control over the exhaust air becomes difficult if not impossible by utilization of such conventional means.
Accordingly, the present invention relates to an improved throttle valve assembly which permits simple and practical control over the flow of air through a straight passage, such as by controlling the speed of exhaust air through a straight passage, whereby the throttle valve assembly of this invention thus overcomes the disadvantages mentioned above.
More specifically, the present invention relates to a throttle valve assembly which can be mounted in a small and compact housing plate having a through straight passage for the air, such as the exhaust air, whereby the housing plate can be simply and compactly mounted directly between a main flow-control valve and its sub-base or manifold. The housing plate has the throttle valve adjustably mounted thereon in intersecting relationship with the straight through passage for adjustably controlling the speed or flow of air therethrough. This throttle valve employs an actuating member which is threadably mounted within a bore formed in the housing plate, which bore is perpendicular to and intersects the through straight passage. The actuating member has a cylindrical sleeve of elastomeric material mounted in surrounding relationship thereon and confined between a pair of axially spaced flanges. This sleeve projects at least part way into the through straight passage and by rotationally threadably adjusting the actuating member, the sleeve is moved axially so as to extend totally across the passage, whereupon one end of the sleeve abuts a shoulder on the housing so that subsequent rotation of the actuating member causes axial compression of the elastomeric sleeve, accompanied by radial expansion thereof, so as to effect sealing of the sleeve with the housing so as to permit a total closing off of the passage.
Thus, one of the objects of this invention is the provision of a throttle valve assembly which permits control of flow through a straight flow passage, whereby the resultant throttle valve assembly can be a simple and economical structure which can be incorporated within a relatively flat plate or housing to facilitate its use in a simple and efficient manner directly between a main valve assembly and its sub-base or manifold.
It is also an object of this invention to provide an improved throttle valve assembly, as aforesaid, which permits the flow to be simply but precisely adjusted, with the flow through said passage being adjustable throughout a range which extends from a fully closed to a fully opened position.
Other objects and purposes of the invention will be apparent after reading the following specification and inspecting the accompanying drawings.